Related Party Transactions (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 16, 2017	Dec. 31, 2016	Aug. 01, 2014	Mar. 16, 2012
Related Party Transaction [Line Items]
Securities purchased under agreements to resell	$ 141,247,000			$ 94,550,000
Securities sold under agreements to repurchase	71,559,000			26,167,000
Preferred stock	229,475,000			229,475,000
Preferred stock dividends	3,548,000	$ 3,219,000
BSI | Line of Credit | BBVA Compass Bancshares, Inc.
Related Party Transaction [Line Items]
Due from related parties	50,000,000			50,000,000	$ 150,000,000
BSI | Revolving Credit Facility | Line of Credit | BBVA Compass Bancshares, Inc.
Related Party Transaction [Line Items]
Due from related parties	0		$ 450,000,000	0		$ 420,000,000
BBVA
Related Party Transaction [Line Items]
Securities purchased under agreements to resell	989,000			8,330,000
Securities sold under agreements to repurchase	69,860,000			23,397,000
BBVA | BBVA Compass Bancshares, Inc.
Related Party Transaction [Line Items]
Revenue from related parties	6,000,000	3,900,000
Fees on agreements	5,800,000	6,800,000
Derivatives designated as hedging instrument | BBVA
Related Party Transaction [Line Items]
Derivative, notional amount	5,500,000,000			5,200,000,000
Free-standing derivatives not designated as hedging instrument | Free-standing derivative instruments – risk management and other purposes | BBVA
Related Party Transaction [Line Items]
Related party transaction, amount of transaction	(3,490,000)			(14,326,000)
Revolving Note And Cash Subordinated Agreement | BSI | BBVA Compass Bancshares, Inc.
Related Party Transaction [Line Items]
Interest expense	367,000	822,000
Preferred Stock | Series A Preferred Stock | BBVA
Related Party Transaction [Line Items]
Preferred stock	229,000,000
Preferred stock dividends	3,500,000	$ 3,200,000
Cash flow hedges | Derivatives designated as hedging instrument | BBVA
Related Party Transaction [Line Items]
Related party transaction, amount of transaction	433,000			(380,000)
Fair value hedges | BBVA
Related Party Transaction [Line Items]
Related party transaction, amount of transaction	$ (16,169,000)			$ (14,225,000)